Inactivation of muscle chloride channel by transposon insertion in myotonic mice

• Published in: Nature (London) Vol. 354; no. 6351; pp. 304 - 308
• Main Authors: Steinmeyer, Klaus, Klocke, Rainer, Ortland, Christoph, Gronemeier, Monika, Jockusch, Harald, GrÜnder, Stefan, Jentsch, Thomas J
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 28.11.1991; Nature Publishing Group
• Subjects: Amino Acid Sequence; Animal models; Animals; Base Sequence; Biological and medical sciences; Blotting, Northern; Blotting, Southern; Chloride Channels; Chlorides - physiology; Chromosome Mapping; Cloning, Molecular; Disease; DNA - genetics; DNA Transposable Elements; Dystrophy; Gene Expression; genes; Inactivation; Medical research; Medical sciences; Membrane Proteins - physiology; Mice; Mice, Mutant Strains; Molecular Sequence Data; Muscles; Muscular system; myotonia; Myotonia - genetics; Nervous system involvement in other diseases. Miscellaneous; Neurology; RNA Splicing; RNA, Messenger - genetics; transposons; Animal model; Nervous system diseases; Chlorine; Myotonia; Pathogenesis; Transposon; Rodentia; Ionic channel; Striated muscle; Striated muscle disease; Vertebrata; Mammalia; Mouse; Animal; Genetics; Molecular biology
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/354304a0

MYOTONIA (stiffness and impaired relaxation of skeletal muscle) is a symptom of several diseases caused by repetitive firing of action potentials in muscle membranes. Purely myotonic human diseases are dominant myotonia congenita (Thomsen) and recessive generalized myotonia (Becker), whereas myotonic dystrophy is a systemic disease. Muscle hyperexcitability was attributed to defects in sodium channels and/or to a decrease in chloride conductance (in Becker's myotonia and in genetic animal models). Experimental blockage of Cl- conductance (normally 70-85% of resting conductance in muscle) in fact elicits myotonia. ADR mice are a realistic animal model for recessive autosomal myotonia. In addition to Cl- conductance, many other parameters are changed in muscles of homozygous animals. We have now cloned the major mammalian skeletal muscle chloride channel (ClC-1). Here we report that in ADR mice a transposon of the ETn family has inserted into the corresponding gene, destroying its coding potential for several membrane-spanning domains. Together with the lack of recombination between the Clc-1 gene and the adr locus, this strongly suggests a lack of functional chloride channels as the primary cause of mouse myotonia.